Plate for fixing the bones of a joint, in particular a metatarso-phalangeal joint

ABSTRACT

A plate for fixing the bones of a joint, in particular of a metatarso-phalangeal joint, for the purpose of performing arthodesis. The plate comprises two sections, respectively a proximal section and a distal section, each section having a respective longitudinal axis of symmetry S 1 , S 2  such that the projection onto a horizontal plane of the axis of symmetry S 2  of the distal section presents an angle of inclination relative to the projection of the axis of symmetry S 1  of the proximal portion, the projections inserting at a point A. The projection onto a vertical plane of the axis of symmetry S 2  presents an angle of inclination relative to the projection of the axis of symmetry S 1 , their intersection taking place at a point A 2  which is distinct from the point A 1 .

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of pending U.S. patentapplication Ser. No. 10/255,204, filed on Sep. 26, 2002 and entitled“PLATE FOR FIXING THE BONES OF A JOINT, IN PARTICULAR AMETATARSO-PHALANGEAL JOINT”, incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the general technical field of surgicaldevices for fixing together and aligning the two bony parts of a jointrelative to each other, and in particular a joint including thephalanges of a toe or a finger in order to perform arthrodesis.

The present invention relates to a plate for fixing together the bonesof a joint, in particular a metatarso-phalangeal joint, in order toperform arthrodesis.

In a preferred but non exclusive application of the invention, thefixing plate is more particularly, but not exclusively, intended anddesigned for setting an angular position and then performing arthrodesison a metatarso-phalangeal joint. However, it should be understood thatin the meaning of the invention applications to other joints can beenvisaged, whenever the purpose is to bond the two bony parts of a jointtogether in a fixed relative position.

BACKGROUND OF THE INVENTION

In the event of arthrosis in joints between bones, and in particular ina metatarso-phalangeal joint, it is often necessary to performarthrodesis in order to fuse the two bones together. As a general rule,arthrodesis constitutes an operation that is difficult in that it sets ajoint in a position that is defined and it does so in a manner that isnot reversible. Thus, it is very important for arthrodesis of ametatarso-phalangeal joint to be performed correctly insofar as thejoint is involved as an essential actor in the walking cycle of a humanbeing. It will thus be understood that it is essential for the two bonesto be positioned relative to each other prior to fusion with anorientation that is implemented as accurately as possible in order toavoid any subsequent difficulty.

It is therefore essential for the axes of the bones to be fixed relativeto each other so as to comply as well as possible with the flexing andthe axes of the patient, and this must be done as a function of thepatient's sex, gait, and morphology.

Until now, metatarso-phalangeal arthrodesis has been performed usingfixing plates of a variety of shapes and provided with slots forreceiving fixing screws in order to secure the plate to each of the twobones to be fused together.

Thus, by way of example, fixing plates are known that present a curved“quarter-tube” cross-section which the surgeon places across the jointbetween the bones to be fused together. That known plate is bent by thesurgeon so as to take up an angle in the dorsi-flexion plane having avalue that has been determined by the surgeon and that is specific tothe patient. Once a joint has been blocked, plates of that type thusmake it possible to confer a particular orientation in elevation on oneof the two bones on which arthrodesis is performed. This constitutes anadvantage to the patient since the joint is blocked under conditionsclose to normal conditions of use for that joint, thereby reducingdifficulty for the patient while walking and reducing possible futurecomplications.

Nevertheless, fixing plates of that type turn out to suffer from avariety of drawbacks, and in particular they are quite difficult for thesurgeon to bend. In addition, it turns out that bending is rarelyperformed with sufficient accuracy and that bending gives rise todeformed zones of the plate presenting edges that can be quite sharp andlikely to generate irritation or inflammation on coming into contactwith adjacent tissue such as tendons, muscles, ligaments, skin, etc.Finally, plates of that type are unsuitable for bending through avarus-valgus angle, which means that they are not capable ofimplementing arthrodeses that are sufficiently close to conditions ofoptimum geometrical orientation between the two bones to be fusedtogether for the purpose of reducing to the greatest possible extent anyrisk of subsequent difficulties and complications for the patient.

Fixing plates that are completely plane are also known, and althoughthey greatly reduce the risk of complications for the patient followingthe operation of installing them, insofar as no bending is performed,they nevertheless do not make it possible to perform an arthrodesis inwhich the bones present specific dorsi flexion and varus-valgus angles.

As a general rule, it also turns out that fixing plates for bending bythe surgeon require a special bending tool to be used that is specificto each type of plate, thereby constituting a further constraint.Finally, it turns out that a fixing plate that has been bent suffersfrom weakening of its metal in the bend zone, and that can constitute adrawback in terms of strength. Furthermore, the need to provide openingsthrough the plate for passing fixing screws complicates the operation ofbending the plate, specifically because of the presence of saidopenings.

OBJECTS AND SUMMARY OF THE INVENTION

Consequently, the object of the invention is to remedy the variousdrawbacks set out above and to propose a novel plate for fixing thebones of a joint, in particular a metatarso-phalangeal joint, for thepurpose of performing arthrodesis between two bone fragments under goodconditions while ensuring that the relative orientation of the two bonesto be fused together is determined with excellent accuracy.

Another object of the invention is to propose a novel plate for fixingthe bones of a joint that makes it easier to put the plate into placeand to seek a precise geometrical orientation.

Another object of the invention is to propose a novel plate for fixingthe bones of a joint with improved placing of the plate.

Another object of the invention is to propose a novel plate for fixingthe bones of a joint that is particularly well adapted to the anatomy ofthe bones to be fused together.

Another object of the invention is to propose a novel plate for fixingthe bones of a joint that is suitable for being adapted to variouspossible anatomical configurations.

The objects given to the invention are achieved by means of a plate forfixing the bones of a joint, in particular a metatarso-phalangeal joint,for the purpose of performing arthrodesis, wherein:

the plate comprises two sections, respectively a proximal section and adistal section, each section presenting a respective longitudinal axisof symmetry S₁, S₂ said plate being designed to be placed across thejoint, the axes S₁ and S₂ being parallel and aligned with thelongitudinal axes of the two bone fragments to be fused together suchthat the projection onto a horizontal plane of the axis of symmetry S₂of the distal section is inclined at an angle α relative to theprojection of the axis of symmetry S₁ of the proximal portion, theprojections intersecting at a point A₁; and

the projection onto a vertical plane of the axis of symmetry S₂ presentsan angle of inclination β relative to the projection of the axis ofsymmetry S₁, the projections intersecting at a point A₂ which isdistinct from the point A₁, the distal section extending over a firstlength fraction L₁ away from the proximal section while remaining in thesame plane P₁ as the proximal section.

BRIEF DESCRIPTION OF THE DRAWING

Other advantages and objects of the invention appear in greater detailon reading the following description made with reference to theaccompanying drawing that is provided purely by way of non-limitingexplanation and in which:

FIG. 1 is a diagrammatic perspective view showing a plate for fixing thebones of a joint in order to perform arthrodesis, the plate being shownin position on a metatarso-phalangeal joint;

FIG. 2 is a plan view corresponding to a horizontal plane showing aplate of the invention for fixing together the bones of a joint, theplate turning to the left; and

FIG. 3 is a fragmentary side view corresponding to a vertical planeshowing a plate of the invention for fixing together the bones of ajoint.

MORE DETAILED DESCRIPTION

FIGS. 1 to 3 show a fixing plate 1 in position and fixed to ametatarso-phalangeal joint for the purpose of performing arthrodesisbetween a metatarsal bone M and a phalangeal bone P.

Nevertheless, in the meaning of the invention, the fixing plate 1 of theinvention could be used with appropriate anatomic shape and size forperforming arthrodesis of some other joint, in particular for a joint inthe hand when performing surgery of the hand.

The fixing plate 1 of the invention is in the form of an elongate bodyof plane cross section, for example, e.g. made of metal and ofsufficient stiffness to provide a junction between the bones of thejoint that are to be fused together and to provide firm support.

In accordance with the invention, the fixing plate 1 comprises twosections 2 and 3, respectively a proximal section and a distal section,each section presenting its own longitudinal axis of symmetry,respectively referenced S₁ and S₂.

Each section 2, 3 can thus be considered in general terms as a bodyhaving a thickness of a few millimeters and a length that is longer thanits width so as to form a geometrical shape that is approximately thatof a rectangular parallelepiped.

The proximal section 2 is for placing and fixing substantially on themetatarsal bone M, while the distal section 3 is for placing and fixingsubstantially on the phalangeal bone P in order to perform arthrodesisbetween these two bone fragments, the plate 1 thus being placed acrossthe joint, with the axes of symmetry S₁ and S₂ being parallel and inalignment with the longitudinal axes of symmetry of the bones.

In conventional manner, fixing is performed by means of screws (notshown in the figures) which the surgeon screws into the bones through aseries of slots 4 formed in the fixing plate 1, and in particular ineach of its sections 2, 3 for the purpose of passing the fixing screws.

As shown in the figures, the proximal section 2 is advantageously longerthan the distal section 3 while being of equal thickness and of widththat is likewise equal. Because the proximal section 2 is longer, itadvantageously has a larger number of orifices 4, for example it hasthree orifices while the distal section 3 has two orifices 4, and theorifices can be of any suitable shape, for example circular or oblong.

Alternatively the distal and proximal sections 3 and 2 areadvantageously of identical length. In any event, the distal andproximal sections 3 and 2 are adjacent and form a single part.

This dimensional characteristic enables the fixing plate to be betteradapted to the anatomy of the bones to be fused together and it improvesthe supporting and holding ability of said plate.

Advantageously, the two sections 2 and 3 are plane and rectilinear, itbeing understood that in a variant the cross sections of the proximalsection 2 and of the distal section 3 could be curved to some extent,preferably equally, so as to provide a better fit to certain particularanatomical configurations.

According to an important feature of the invention, and as shown inparticular in FIG. 2, the axes of symmetry S₁ and S₂ are not inalignment with each other, but on the contrary present a certain angleof inclination so that the two sections present respective inclinationsin the horizontal plane. Thus, in accordance with the invention, theprojection of the axis of symmetry S₂ of the distal section 3 onto ahorizontal plane presents an angle of inclination α relative to theprojection of the axis of symmetry S₁ of the proximal portion 2, theseprojections intersecting at a point A₁.

This feature makes it possible to impart an accurate and pre-establishedvarus-valgus angle on the phalangeal bone relative to the metatarsalbone, the axes of symmetry S₁ and S₂ of the plate 1 being intended formounting by a surgeon so as to be strictly parallel to the longitudinalaxes of the two bone fragments M and P that are to be fused together.

In accordance with the invention, this angle of inclination α lies inthe range 5° to 20° and is preferably about 10. It is specified that theangle of inclination α between the proximal and distal sections 2 and 3is of a value that is fixed and specific to the fixing plate 1 of theinvention, thus avoiding any need for the surgeon to bend the plateduring the operation as is the case in the known prior art. The distalsection 3 can be inclined either to the left or to the right relative tothe proximal section 2.

According to another important characteristic of the invention, thefixing plate 1 is such that the projection onto a vertical plane (FIG.3) of the axis of symmetry S₂ presents an angle of inclination βrelative to the projection of the axis of symmetry S₁, these projectionsintersecting at a point A₂which is distinct from the point A₁.

According to this important characteristic of the invention, and asshown in particular in FIGS. 1 and 3, the distal section 3 extends awayfrom the proximal section 2 over a first length fraction L₁ while lyingin the same plane P₁ as the proximal section 2, said first lengthfraction L₁ being extended by a second length fraction L₂ which extendsin a plane P₂ forming an angle with said plane P₁, and specifically theangle β. The angle β enables the phalangeal bone P to be given adorsi-flexion angle that is accurate and pre-established.

According to this characteristic, the sum of the lengths L₁ and L₂corresponds to the total length of the distal section 3 starting fromthe line of inclination A (FIG. 1) marking the change in directionbetween the two sections 2 and 3. Thus, the proximal and distal sections2 and 3 are connected together directly without a connection zone, andthey are tangential to the single radius of curvature forming theirconnection.

According to this characteristic, the fixing plate of the invention hastwo distinct inclinations, one in the horizontal plane corresponding tothe line A and to the angle α responsible for the varus-valgus angle,and the other corresponding to the line B and to the angle β responsiblefor the dorsi-flexion angle, the two inclination zones of the plate notcoinciding, but on the contrary being offset from each other, with thechange of inclination B being situated in a position that is distalrelative to the line A.

Advantageously, the angle β lies in the range 5° to 20°, and ispreferably about 10°. This angle β can be modified by the surgeon beforeor during surgery.

This disposition makes it possible to obtain a better match between thefixing plate 1 and the various bony parts to be fused together, sinceonly the terminal fraction L₂ of the distal section 3 presents twoangles of inclination, one in the horizontal plane and the other in thevertical plane, while the other fraction of the distal section presentsonly one angle of inclination, which angle is in the horizontal plane.

According to a particularly advantageous characteristic of theinvention, the fixing plate 1 is provided with an intermediate fixingorifice 5. Advantageously, the intermediate fixing orifice 5 is situatedat the intersection of the axes of symmetry S₁ and S₂. i.e. on theinclination line A, and it corresponds to the point A₁. This orificeenables the surgeon to fix the fixing plate 1 temporarily in registerwith the center C of the head of the metatarsal bone M by means of a pinprior to installing the final fixing screws through the slots 4.

The fixing plate of the invention is put into place as follows: aftermaking an incision over the joint to be fused, the surgeon mills or cutsthe faces of the joint so as to remove the arthrodesis present in thejoint. Thereafter the surgeon puts the two bones to be fused togetherinto position relative to each other and places the fixing plate 1 ofthe invention on the top faces of the bones M and P.

This positioning must be done while taking care to ensure that thefixing plate 1 is placed in such a manner that its axes of symmetry S₁and S₂ are strictly parallel and aligned with the longitudinal axes ofthe two bone fragments M and P to be fused together. The surgeon mustalso take care to position the proximal section 2 in such a manner thatthe intermediate fixing orifice 5 is substantially in register with thecenter C of the head of the metatarsal bone M so as to achieve the bestpossible match between the plate and the bony parts. Fixing proper ofthe bones in the required geometrical configuration is then performednaturally because of the two natural angles of inclination of the fixingplate of the invention, which angles are fixed and pre-established.

The fixing plate of the invention thus makes it possible simply,quickly, and accurately to perform arthrodesis of the bones of a jointin a geometrical configuration that is accurate and pre established.

1. A surgical device comprising: a plate having a plurality of holes forreceiving respective screws to fix the plate to at least one bone,wherein the plate further comprises: a first portion comprising anelongate body extending along a first axis through a first plane andcomprising at least one of the plurality of holes; and a second portioncomprising an elongate body comprising at least one of the plurality ofholes, the second portion comprising a first length and second length,the first length extending along a second axis and through the firstplane, the second axis of the first length having a pre-establishednon-zero angle α with respect to the first axis of the first portion,the second length of the second portion extending along a third axis andthrough a second plane different from the first plane, the second planeof the second length having a pre-established non-zero angle β withrespect to the first plane, wherein the first axis and the second axisintersect at a point A₁, and the projection of the third axis onto thefirst plane intersects with point A₁.
 2. A plate for fixing the bones ofa metatarso-phalangeal joint in order to perform arthrodesis, said platehaving a plurality of holes for receiving respective screws to fix theplate to the bone fragments to be fused together, wherein the platefurther comprises a first portion comprising an elongate body whichcomprises at least one of the plurality of holes and a second portioncomprising an elongate body which comprises at least one of theplurality of holes, the projection onto an horizontal plane of thesecond portion having a pre-established non-zero angle α with respect tothe projection onto an horizontal plane of the first portion, and theprojection onto a vertical plane of the second portion having apre-established non-zero angle β with respect to the projection onto avertical plane of the first portion.